On Mon, 28 Apr 2008, Jon Clayden wrote:
> Hi,
>> A piece of my code that uses readBin() to read a certain file type is
> behaving strangely with R 2.7.0. This seems to be because of a failure
> to match() strings after using rawToChar() when the original was
> terminated with a "\0" character. Direct equality testing with ==
> still works as expected. I can reproduce this as follows:
>>> x <- "foo"
>> y <- c(charToRaw("foo"),as.raw(0))
>> z <- rawToChar(y)
>> z==x
> [1] TRUE
>> z=="foo"
> [1] TRUE
>> z %in% c("foo","bar")
> [1] FALSE
>> z %in% c("foo","bar","foo\0")
> [1] FALSE
>> But without the nul character it works fine:
>>> zz <- rawToChar(charToRaw("foo"))
>> zz %in% c("foo","bar")
> [1] TRUE
>> I don't see anything about this in the latest NEWS, but is this
> expected behaviour? Or is it, as I suspect, a bug? This seems to be
> new to R 2.7.0, as I said.
And so is the comment in ?match:
Character inputs with embedded nul bytes will be truncated at the
first nul.
The bug is in the documentation here -- this was intentional.
As support for embedded nuls in character strings is being removed in R
2.8.0, you should not rely on this.
--
Brian D. Ripley, ripley at stats.ox.ac.uk
Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/
University of Oxford, Tel: +44 1865 272861 (self)
1 South Parks Road, +44 1865 272866 (PA)
Oxford OX1 3TG, UK Fax: +44 1865 272595